Rolling mill position control



Aug. 24, 1965 c. F. HAUTAU ROLLING MILL POSITION CONTROL 2 Sheets-Sheet1 Filed Nov. 13, 1961 INVENTOR. CHARZJ ES F HAUTAU M @A I47'TORIVE) 1965c. F. HAUTAU 3,201,962

ROLLING MILL POSITION CONTROL Filed Nov. 13, 1961 2 Sheets-Sheet 2CHARLES F. FQ XWAU United States Patent 3,201,962 ROLLING MILL POSITIUN(IUNTRQL Charles F. Hautau, 146 Hilltop Road, flxford, Ohio Filed Nov.13, 1961, Ser. No. 151,924 7 Claims. (Cl. 72-9) This invention relatesto apparatus for adjusting the product thickness in rolling mills, andmore particularly to apparatus for thermally controlling the rollspacing in such mills.

The conventional rolling mill consists of a pair of rotatablecylindrical rolls disposed with their axes in parallel relation andtheir ends journaled in bearings. At least one of the rolls and itsbearings are movable in a plane passing through the axes of both rolls.The rolling operation is accomplished by passing metal sheets or stripsbetween the rolls, the roll spacing having been preset to a value lessthan the thickness of the metal. As the metal is passed through the gapbetween the rolls, it is squeezed to a reduced thickness correspondingroughly to the size of the roll gap.

Adjustment of the roll spacing is normally achieved by rotation of largepower-activated screws. The axes of the screws lie in the plane passingthrough the axes of both rolls and extend perpendicularly to the axes ofthe roll-s. The screws are attached to adjusting blocks or pads which inturn are fixed to the bearings of the adjacent roll so that rotation ofthe screws causes movement of the roll and a change in the size of thegap between the rolls.

The forces exerted on the rolls by the metal sheet or strip during therolling operation are often substantial and since the rolls aresupported only at their ends, bowing of the rolls may occur. To preventsuch distortion of the rolls, back-up rolls, consisting of largerdiameter journaled rolls disposed with their axes parallel to the axesof the standard rolls and situated immediately adjacent the standardrolls, are frequently employed to provide additional support.

Although the roll spacing may be adjusted by rotation of the screws toproduce a desired product thickness at a given moment, constantvariations in the hardness and thickness of the incoming metal willresult in an uneven product thickness unless means are provided tocontinu-ally measure the product thickness and utilize such informationto adjust the roll spacing. Precise-thickness gages are available whichconvert the product thickness readings into electrical signals. Theoutput from these gages may be fed back to the screws in order to adjustthe roll gap. Due to the size and inherent inaccuracy of these screws,however, small controlled increments of adjustment are unattainable inpractice. The lack of precision typical of this conventional adjustingmeans is especially critical in the rolling of very thin stock such asfoil. Although precise-thickness gages maybe accurate in measuring theproduct thickness within millionths of an inch, such gaging informationis of no value unless means are available for utilizing that informationto make incremental adjustments of the roll gap.

. r The present invention contemplates a system in which precise gaginginformation is utilized to control thermal expansion and contraction ofblocks of steel or other suitable material located immediately adjacentthe rolls in such manner that expansion or contraction of the blocksinduces a corresponding decrease or increase in the size of the gapbetween the rolls.

In a preferred embodiment of the present invention which will besubsequently described in detail, the blocks are interposed between theadjusting pads and the journaled ends and bearings of the back-up rollsin a conventional four-high rolling mil-l. The screws are rotated so iceas to adjust the rolls roughly to the desired spacing. A temperaturecontrolled fluent is arranged to circulate through channels in theblocks causing thermal expansion and contraction of the blocks. As thedimensions of the blocks vary, the working rolls are moved, altering thesize of the roll gap; expansion of the blocks moves the working rollscloser together, reducing the roll spacing, while contraction of theblocks increases the separation or gap between the rolls.

A precise-thickness gage, positioned immediately after the rolls,measures the thickness of the metal as it issues from the rolls andtransmits this information in the form of electrical signals to an errordetector circuit. The desired thickness is similarly transmitted to thiscircuit which derives the algebraic difference between the two signalsto regulate the flow of hot and cold fluent through servo valves intothe block. A pump circulates the fluent through the blocks and maintainsthe pressure in the system. As the servo valves are opened andadditional fluent introduced to the blocks, the excess fluent overflowsinto a sump. This arrangement allows fluent to be continuouslycirculated until a roll gap adjustment is required and a servo valveopened.

An alternative method of supplying temperature controlled fluent to theblocks consists of utilizing continuously flowing streams of hot andcold fluent as a fluent source. The two streams pass through a mixingvalve which is actuated by the output signal from the error detectorcircuit so as to allow the correct mixture of hot and cold fluent topass through to the blocks. This mixture will have a temperaturesuitable to vary the size of the roll gap so as to result in a productthickness equal to the desired thickness.

It is therefore an object of the present invention to provide in arolling mill, a positioning system for controlling the roll spacingconsisting of expansible blocks situated between the screws and therolls, having interior channels into which is introduced fluent that ismaintained at a temperature suitable to expand or contract the blocks insuch fashion that the roll gap is increased or decreased to vary thedesired thickness.

Another object of the present invention is to provide in a conventionalrolling mill, apparatus for controlling the roll spacing consisting of aprecise-thickness gage which measures the product thickness, and anelectrical circuit which utilizes the gage information as to departuresfrom the desired product thickness to control the entry of temperaturecontrolled fluent into channels in an expansible block situated betweenthe screws and the journaled end of the rolls.

Other objects and advantages will be more readily apparent from thefollowing detailed description of a preferred embodiment of the presentinvention. The description makes reference to the accompanying drawingsin which:

FIG. 1 is a perspective View of a preferred embodiment of the pesentinvention, with parts broken away.

FIG. 2 is a schematic view of the hydraulic and electrical systemsemployed with the structure of FIG. 1.

FIG. 3 is a detailed side view of the expansible metal block shown inFIG. 2, with parts broken away.

The invention is illustrated as employed in a conventional four-highrolling mill. Two cylindrical rolls 1t and 12 having ends 14- and 16journaled in bearings 18 and 20 are disposed with their axes inhorizontal parallel relation. The rolls 10 and 12 are situated adjacentone another defining a rectangular gap or space 22 through which themetal sheet or strip 24 is passed. Back-up rolls 26 and 28, of largerdiameter than the Working rolls 1t) and 12, are disposed with their axesparallel to the axes of the working rolls and are in contact with them.The back-up rolls 26 and 28 have ends 30 and 32 journaled in bear of theworking-rolls 10. and 12.

A frame 37 having vertical members 38and. a hori- V zontal deck 39supports two motors 40 and 42, each hav.

ing output'through a right-angle drive 48 and 50 situated on the surfaceof the'deck39; The bearings '18, 20, 34

and 36 are supported between the vertical'members38 so as tobe free forvertical movement." Screws 52jfixed at' their. upper ends to the deck39'and journaled along theirj upper length in bearings 53 in the deck,terminate .at' their lower ends in nuts 54 which are fixedly attached'todistributing or adjusting pads 56 which distrihutethe" 7 force exertedby the screws over a larger area. i r r Expansible blocks 58 of steel orother suitable material are interposed between andpermaneritly afiii'redto the bearings 34 of the upper back-up r'oll 26andthedistributing pads56. Similar expansible blocks 60 are situated between'the bearings 360ithe lower back-up roll28 and a 3 support pad 62. The. blocks 58 'an d'60jare fitted with" channels 62tthrough which a fluent is arranged tocircu- 1 late, All four of the blocks 58 and 60'are connected to asingle hydraulic and electrical system.. Fluent'is stipplied from hotandcold reservoirs 64 and 66 where the; fluentis maintained at a fixed,known temperature and is; transferred under pressurethrough hotand coldinlet lines 7 6S and 70, each having aservo'valve 72 and 74, to a pump76. The 'pump 76 forces the fluent'throu'gh thevchannels t a 62 intheblocks 58 and tl and'maintains a constant pres- V sure'in'thersystem.Thefluent is moved through, the systern between the pump 76 and the .lblQCkSr 58 and 60 through a network of tubing78 Whichis'connected to;the

block by nozzles 80 A'sump 82 'is'positioned' sufficiently j higher inelevation than the blocks 58' and 60 and pump 76 so that the sumpreceives fluentfrom the'system only when one of the'servo valves 72,. 74is, opened and hot or cold fluent allowed'to enter.

The electrical system is comprised of an-errorfdetector circuit oranalog substracter 84'which determinesthe algebraic'dififerences of twoinput signals. One inputsignal is f produced by aprecise-thickness gage'86'whicih is located immediately after the rolls 10 and 12 so as tomeasure the'pr'oduct thicknessas the metal'issues from the rolls;

The gage'86, which maybe'an X-ray or nuclear thickness gage or mayconsist of a precision micrometerdevice, transmitsrto the detectorcircuit 84-a signal which is'prog 'portional to'thethickness readinglofthe gage; The seci ond input signal is supplied by a potentiometer 88whichis preset to tr ans'mitta signal equal inmagnitude to. that'transmittedby, the gage 86 when metal of the desired thickness ispassed through the gage. V, 7 r

a The detector circuit v84 produces a signal which is theatlgebraicdifierence ofthe tworinput Signals and trans-r j mits it to a'single-pole' doubleethrow polarized relay 90; which is connected to eachof the servofvalves 72 and 74:

As the signal reaches the relay 99, the relayfwill close the circuitleading to one of the servo valves 72 1and,74 and a signal equalito thealgebraic difierence of the two. input;

signals will be transmittedto the servo valves 72. and .74; a

the algebraic sign of the outputsignalfrom the error detector 84determines'which'of the servo valves 72, 7 4 will be activated Themagnitude of-the output signalf trans-1 mitted to the'valves 72 and 74controlslth cxtent -to which the valve -is opened, thus' determiningthelrate of flow of fluent through thevalves-72an-d'74.

The electrical'system is'arrangedso that the output signal from theerror detector circuit-84,wl1ich istrans f mitted whentheproduct-thickness feiiceedsthe desired thickness,.will open the:servoval ve '72 mine-net inlet line 68 sufliciently .to'allow hot marinaenter the blocks product thickness "equal tothedesired thickness f VSimilarly, if the produ: t thickness is lessthanltheide j.sired'thickness, thefiow of cold fluent must'be sufficient-f,

rto result'in a productthickness equal to the desired thickness. Iftheproduct thickness equals the desired thickness, no signal will betransmitted fromthei subtracter i circuit 84'since the two input signalswill be. numerically equal. As a result, the relay'90 willnot-beactivated and the servo valveswill remain closed. The" pump 76ivill thenrecirculate the fluent already flo wi ng in the system. 7 In operation,the motors 40 and-'42 are activated to rotate the screws:52'unti1 therollf gap 22 closely matches I the thickness of'the incoming rnetal'24.; The potentiomlQ eter' SS isset tojtransrnitfa signal correspondingin'magn'itudejto the signal'emitted by the thickness gage 86 when metalof the desired thickness is passed throughhthe gage86. r"The'working'irollsj10 1and 12' are:rotated bypowet '15 means "(notshown). j The'metal' sheet 24 is passed through theroll. gapj'22 and thegage86. Departures of the product" thickness from the desired thicknessare communicated to thea'p'propria'te servo valves 72 and 74; the flow,of fluent at anew temperature through the-blocks 58 and 6t) causesatcorresponding expansion'gor.contractioniof the Yblocks This, in turn;causes a change in the spacing of c the workingrolls 10. and 12;expansion of'the blocks 58 and 60 reducezthe roll; gap 22 :while.contraction of the 'blocks58 and 60 increases the roll'gap Y Theefi-ctof this expansion or contraction of the blocks 58, 60orr-theproductthickness will benoted by the'thickness gage-8 6. The newsignal emitted by the gage86 will direct further openingor closing ofthe servo valves 72 and '74. This process-is, continued until theproduct thickness 'exa ctlytequals the? desired thicknes'sQat which timethe fluent the servo-valves 72 and 74 will be closedand in the blocks 58and 60 recirculated; t

1 An alternative positioning system consists of two gages 86',each'located at .gppositeedges of the metal as i't 'is- 35 sues from therolls wand 12; Each gage is connected i to an'independentfhydraulic andelectric system of the type previously described in detail; eachhydraulic system feeds fluent into .the'pair ofiblock's 58 and 69located on the same edge'ofithe metal: sheet 24as'thev gage. ,With thisarrangement the present invention can be adapted to produce a productsheet, having a thickness which, varies unifermlyffrom edge to'edgeythismay be accomplished simply by settingqeach of the otentiometers 88 at adifferent value; a I i t An alterna 've method-oftransferring'heat withrespect to the expansible blocks or material consists of the use ofelectrical resistors as heating elements" in conjunctionwith'asuitable'cooling process. Q 1 Although the presentfinvention hasbeenillustrated in c'onjunction'with .afour-high rolling mill, it maybeemployed in a similar manner in conventional'rolling mills or any size,having any number, of standard' or back-up -r olls.

Having described the inventionin its simplest terms, it iSftObe-understood that the, features: of construction "ma be: changed andvariedrin'r greateror lesserv degree "withqutdeparting from the essenceof 'theinvention'fdea fined in the .append'edclaims; 1 claim: a 1 ,7

LfIn' a rolling millfihaving astationary "frame, and cylindricalrollsdisposedwiththeiraxes, parallel to'jone 4 another and journaled,inbearings whichgare 'jmovable ,7 within said frame, -a positioningfsystem'tor' controlling the'spa'cing between said rolls, comprising? ithe thicknessof the rolled gage; means-tor, measuring 'x-proglucty"fand'zmeans, under the control of the gage'fmea'ns; for

i j maintaining :said' material at a temperature a function ofthere'ading otjsaid gage. 7 t

. 2.31 1 ar'olling mill havi'ng a's't'ationary frame; andcylindricalirolls disposed; with their axes parallel-to .one, an-

?fin' saidz frame, a; positioning'system forv controlling the :spacingbetweensaid rolls,[co mprising;

expansible material 'fixed'totlie bearings of said @0118;

which 'is t otherand journaled-in bearingsiwhich' are movable with-texpansible metal blocks fixed to the bearings of said rolls, said blockshaving interior channels adapted to receive fluid;

rotatable screw means each having one end attached to said frame and asecond end attached to one of said blocks, the axes of said screw meanslying in the plane of the axes of both of said rolls and extendingperpendicularly to the axes of said rolls;

means for rotating said screws so as to move said blocks and saidbearings within said frame;

and means for introducing fluid at controlled temperatures into saidchannels in said blocks.

3. In a rolling mill having a stationary frame, and cylindrical rollsdisposed with their axes parallel to one another and journaled inbearings which are movable within said frame, a positioning system forcontrolling the spacing between said rolls, comprising:

expansible metal blocks fixed to the bearings of said rolls, said blockshaving interior channels adapted to receive fluid;

rotatable screw means each having one end attached to said frame and asecond end attached to one of said blocks, the axes of said screw meanslying in the plane of the axes of both of said rolls and extendingperpendicularly to the axes of said rolls;

means for rotating said screws so as to move said blocks and saidbearings within said frame;

gage means for measuring the thickness of the rolled product;

and means, under control of the gage means for maintaining the fluidintroduced into said channels at a temperature which is a function ofthe product thickness.

4. In a rolling mill having a stationary frame, and cylindrical rollsdisposed with their axes parallel to one another and journaled inbearings which are movable within said frame, a positioning system forcontrolling the spacing between said rolls, comprising:

a source of fluid;

expansible metal blocks fixed to the bearings of said rolls, said blockshaving interior channels adapted to receive fluid from said source;

rotatable screw means each having one end attached to said frame and asecond end attached to one of said blocks, the axes of said means lyingin the plane of the axes of both of said rolls and extendingperpendicularly to the axes of said rolls;

means for rotating said screws so as to move said blocks and saidbearings Within said frame;

gage means for measuring the thickness of the rolled product;

servo valves situated between said source of fluid and said blocks;

and means for actuating said servo valves as a function of said productthickness.

5. In a rolling mill having a stationary frame, and cylindrical rollsdisposed with their axes parallel to one another and journaled inbearings which are movable within said frame, a positioning system forcontrolling the spacing between said rolls, comprising:

a reservoir of hot fluid;

a reservoir of cold fluid;

expansible metal blocks fixed to the bearings of said rolls, said blockshaving interior channels adapted to receive fluid from said reservoirs;

rotatable screw means each having one end attached to said frame and asecond end attached to one of said blocks, the axes of said means lyingin the plane of the axes of both of said rolls and extendingperpendicularly to the axes of said rolls;

means for rotating said screws so as to move said blocks and saidbearings within said frame;

gage means for measuring the thickness of the rolled product, said gagemeans being adapted to transmit a signal proportional in magnitude tothe measured product thickness;

means for supplying a signal proportional in magnitude to the desiredproduct thickness;

servo valves situated between each of said reservoirs and said blocks;and means provided for receiving said signals and producing a signalwhich is a function of the difference between said desired and saidmeasured thicknesses, said last signal being adapted to actuate saidservo valves. 6. In a rolling mill having a stationary frame, andcylindrical rolls disposed with their axes parallel to one another andjournaled in bearings which are movable within said frame, a positioningsystem for controlling the spacing between said rolls, comprising:

expansible material fixed to the bearings of said rolls; means formeasuring a dependent variable associated with the operation of therolling mill;

and means, under control of the measuring means for maintaining saidexpansible material at a temperature which is a function of saiddependent variable.

7. In a rolling mill having a stationary frame and cylindrical rollsdisposed with their axes parallel to one another and journaled inbearings which are movable within said frame, a positioning system forcontrolling the spacing between said rolls, comprising:

expansible material fixed to the bearings of said rolls;

rotatable screw means each having one end attached to said frame and asecond end attached to said expansible material, the axes of said screwmeans lying in the plane of the axes of both of said rolls and extendingperpendicularly to the axes of said rolls;

means for rotating said screws so as to move said bearings within saidframe; means for measuring a dependent variable associated with theoperation of the rolling mill;

and means, under control of said measuring means,

for maintaining said expansible material at a temperature which is afunction of said dependent variable.

References Cited by the Examiner UNITED STATES PATENTS 1,112,269 9/ 14Crellin 82-900 1,150,885 8/15 Rittenberger 55.1 2,128,826 8/38 Jung80-551 FOREIGN PATENTS 137,260 9/52 Sweden.

WILLIAM J. STEPHENSON, Primary Examiner. LEON PEAR, Examiner.

6. IN A ROLLING MILL HAVING A STATIONARY FRAME, AND CYLINDRICAL ROLLSDISPOSED WITH THEIR AXES PARALLEL TO ONE ANOTHER AND JOURNALED INBEARINGS WHICH ARE MOVABLE WITHIN SAID FRAME, A POSITIONING SYSTEM FORCONTROLLING THE SPACING BETWEEN SAID ROLLS, COMPRISING: EXPANSIBEMATERIAL FIXED TO THE BEARINGS OF SAID ROLLS; MEANS FOR MEASURING ADEPEDENT VARIABLE ASSOCIATED WITH THE OPERATION OF THE ROLLINGMILL; ANDMEANS, UNDEER CONTROL OF THE MEASURING MEANS FOR MAINTAINING SAIDEXPANSIBLE MATERIAL AT A TEMPERATURE WHICH IS A FUNCTION OF SAIDDEPENDENT VARIABLE.